Opinion: Don't try to add stuff to a Super Simple Oscillator

Time after time I see people come here saying something to that effect. And I think they need to be told the Super Simple Oscillator [SSO] is a lousy basis for anything more complex. It’s a weird circuit, it doesn’t lend itself easily to good voltage control, it isn’t designed to provide an output that can very well drive downstream modules. You can sort of force it, like with LMNC’s 2000 Megadrone or with Kassutronics Avalanche VCO but the former is big and costly and doesn’t really make the issues a whole lot better and the latter is described as interesting and pretty good for something as simple as it is, but still a fair bit more complicated than the SSO while still not very good as a synth VCO. You can make pretty simple oscillators with a CD40106 or a TL074 and such oscillators can be used for decent, much more usable synth drivers.

If you want a still very simple circuit that provides more interesting outputs than the SSO build an Atari Punk Console. Or for something a bit more complex, one of the Music From Outer Space noise boxes like the Weird Sound Generator.

If you want to start a synthesizer, the David Haillant Simple VCO looks like a good option. There are others, if you look.

Have fun with the SSO but when you want to get beyond it, leave it behind.


I think this one is a good candidate too, I guess similar to the one you linked with the termocoupling: https://www.youtube.com/watch?v=FiCMjt0mqvI


Yeah, it’s based on an earlier version of Haillant’s oscillator, both have temperature compensation but they do it differently.

Petition: rename it to the super-low-parts-count oscillator. It’s actually not simple at all…


This is a very interesting point. As I see this, there are, generally speaking, two types of oscillators. The “noisemaker” kind, simple and crude that make some “noise” by turning potentiometer and the like, and VCOs that respond to a V/octave (or similar) standard and can be tuned and played in musical instruments. I think that, if anyone’s confused, it’s because the SSO is a noisemaker type of oscillator that tries to pass as a VCO.

I haven’t build a VCO myself yet, as I am working my way through easier circuits, but as far as I’ve read, the options for a decent DIY VCO are the following:

  • A design around the 3340 IC, like the Hero/Sidekick VCO by @analogoutput, the 3340 breakout board by @Sonosus, the “Curtis VCO” by Gerbrand Sterrenburg, or even this design. There are also many commercial options, like the 1222 Performance VCO by LMNC in Kosmo format, and many more options for Eurorack that can be adapted to Kosmo (Kassutronics, etc). If one feels confident enough, they can even try a stripboard layout, or even clone a 3340-based VCO off a vintage synth off a schematic.
  • Adapting another IC to use as a 1V/octave VCO. Thomas Henry has designed VCOs around the XR2260 and the LM566. If you can find these obsolete ICs, there are both commercial, open source and stripboard designs around…
  • Designs based on CMOS ICs. @moritzklein has a design that uses the 40106 Schmitt Trigger, René Schmitz one that uses the 4069 inverters, Thomas Henry has one that uses the CMOS version of the 555 timer, and another one that uses the 4046 PLL.
  • Discrete approaches using op amps, like the David Haillant VCO mentioned above, and variants, including this one by Louis-Pierre Geerinckx), or the Polivoks VCO by Erika Synths (available in github).

The catch with all the designs that do not use the 3340 or one of the obsolete ICs is that they require other fancy parts like thermistors and/or matched transistors and/or OTAs…

Pick your poison, so to speak!


Nice list!

Taking a look at this breadboard circuit by Jordan Aceto:

It may look a good deal more complicated than the SSO. But the stuff on the right is an amplifier plus a bare speaker, standing in for the powered speaker you need to use with the SSO. You could use a powered speaker here and get rid of that half of the circuit (though probably add a couple resistors to divide down the output level). Aside from that it’s one chip, two caps, a pot, and an LDR — hardly more complicated than the SSO. You can forego the LDR but it allows you to vary the pitch by waving your hands or shining a flashlight on it, very cool!

I was present at the workshop this was prepared for, where a bunch of complete novices, many of them teens and pre-teens (teamed with parents) built several of these things successfully.

Thing is, though, it’s not the dead end the SSO is. That same 40106 oscillator is at the core of Moritz Klein’s VCO (linked by @K.ostas above). Added to it is a CV converter so you can play music on it, AC coupling so there’s no DC offset on the outputs, buffering so the outputs can drive downstream modules, and a comparator to give you a pulse wave in addition to the ramp wave output. As noted above you can similarly enhance the SSO, but it ends up not being really any simpler than the Klein VCO, and probably not as good.

I don’t mean to disparage the SSO. It’s good fun. But people are getting the impression it’s something it isn’t, and getting themselves frustrated by trying to turn it into a “simple” synthesizer.


The SSO, as I see its something på play with, though CGS has made a Psych-LFO and even a super-PSYCH-LFO.
Going back to the plaything; I am putting a NoiseToaster together for a grandson and the Soundlab I started building 10++ years ago will maybe gp to my granddaughters. However cooking up a mega-SSO can be fun but just realising it’s limits. Adding an LDR or having multible SSOs interact like in Ray’s WSG are ways to “enhance” the design.
Just a few days ago Elektor published a way to widening the frequency range of it. So I am about trying that version and redo the WSG, just for fun, just for play, and as analogoutput hints, not trying to make a synthesizer out of it.

Here’s the Elektor redesign:

PS. You can do the same trick with the 555.


Interesting ideas. I note that by “Super Simple Oscillator” I mean the reverse avalanche oscillator, not a Schmitt inverter oscillator. The latter, as mentioned above, I think is a better starting point for something more elaborate than the former.

In the opinion of a builder barely out of his first year (me) this is as simple as it gets for an expo vco


Yeah, I think that’s kind of the point of the 3340 — though if you add multiple CV sources, pulse output, PWM, FM, soft and hard sync, output level shifting and scaling, correction of the PWM pitch shift and pulse wave falling edge issues, and a tri to sine converter, it gets way more complicated.

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Luckily, someone has done all of that work for us.


You still have to solder it!